A prior art cathode-ray tube comprises a casing accommodating an electron optic system, a built-in getter pump and a laser screen having a semiconductor member which has mirror layers of both sides and a transparent heat removing support. The laser screen is mounted in the casing by means of an iron, cobalt and nickel alloy ring (Ulasyuk, V. N. Kvantoskopy [Laser Screen Cathode-Ray Tubes] (in Russian). Moscow. "Radio i Svyaz" Publishing House. 1988. p. 105). This is a sealed-off tube in which the laser screen has a cementing layer connecting the semiconductor member to the heat removing support. The cementing layer is formed when the semiconductor member is cemented to the support by means of an adhesive composition. Adhesive compositions which are generally used for this purpose cannot be heated above 150.degree. C. Heat treatment and evacuation of the tube are carried out with cooling of the laser screen. The iron, cobalt and nickel alloy ring is designed for a thermal decoupling of the evacuated casing and laser screen when they are coupled together and during the heat treatment and evacuation.
The iron, cobalt and nickel alloy ring also ensures mechanical strength of the cathode-ray tube in case of a difference between temperatures of the casing and laser screen. The getter pump is used for evacuating gases released during storage and operation of the cathode-ray tube. These gases are released from the laser screen which cannot be subjected to a complete heat treatment in vacuum at a temperature above 400.degree. C. because the cementing layer is decomposed at a temperature in excess of 150.degree. C. The use of the getter pump and iron, cobalt and nickel alloy ring complicate manufacture of the cathode-ray tube. It is difficult to install the laser screen in the casing because the heat removing support, which is made of sapphire, should be metal plated and welded to the iron, cobalt and nickel alloy ring before installation. It should be noted that the getter pump cannot ensure complete removal of gases released during storage and operation of the cathode-ray tube because this pump is not highly efficient in pumping off aromatic hydrocarbons released by the cementing layer. The gases remaining in the casing substantially shorten life of porous metal cathodes generally used in such cathode-ray tubes. Low heat conductance and mechanical strength of the cementing layer also limit service life of the laser screen subjected to high temperature strains induced by electron beams in operation of the cathode-ray tube.